1. Field of the Invention
This invention generally relates to a seal device for the Stirling engine and more particularly to a rod seal device for the piston rod connecting an operating piston of the Stirling engine with a guide piston which serves as a power take-off device such as for example an air conditioner device.
2. Description of the Prior Art
As is seen from the attached FIG. 1, Stirling engine S includes an operating piston 2 in a cylinder to form a compression chamber 3 which is to be connected to an expansion chamber (not shown) through a cooler, a heat exchanger and a heater device (all not shown). As an operating gas, Helium or Hydrogen gas are used to reciprocate piston 1 between the compression chamber and the expansion chamber. Such reciprocating movement of the piston 2 is transmitted to a driving mechanism 12 and is taken out as a mechanical work. Rod 8 connects the piston 2 and the driving mechanism 12 (only a part is shown in the drawing). In order to prevent the leakage of gas from the compression chamber 3 to the driving mechanism, various seal members are provided along the outer peripheral portion of the rod 8. Such seal device includes a scraper seal ring 4, high pressure oil chamber 5, an oil seal ring 6, low pressure oil chamber 7 and another scraper seal ring 4' disposed from top to the bottom as shown in FIG. 1. The two oil chambers 5 and 7 are connected to each other through pump p and check valve for returning the excess oil in the chamber 7 into the chamber 5. In this system, it is necessary to provide an electric circuit to detect the amount of excess oil in the chamber 7 and to actuate the pump correctly.